1. Field of the Invention
The present invention relates generally to medical devices and procedures. More particularly, it relates to a preassembled circuit for use in extracorporeal procedures, such as coronary bypass and univentricular bypass procedures.
2. Description of the Prior Art
Extracorporeal procedures, such as coronary bypass and univentricular bypass procedures, are well known. Generally, in these procedures it is necessary to provide an extracorporeal fluid path to bypass all or a portion of an artery, vein or organ, such as the heart or lungs, to maintain a proper blood flow. Such an extracorporeal fluid path may be required to allow surgery on the affected artery, vein, organ, or portion thereof. Moreover, where an extracorporeal bypass circuit provides an artificial fluid path for an affected organ, it also may be necessary to provide apparatus for supporting an organ function. For example, during coronary bypass procedures, an extracorporeal circuit may provide a blood pump and oxygenator for supporting the heart and lung functions. Thus, an extracorporeal procedure generally includes a first cannula inserted in a vessel upstream of the affected site, a second cannula inserted in the vessel downstream of the affected site, and a series of tubes and, if required, additional support apparatus such as a pump and the like, attached in fluid communication between the two cannulae.
Recently, a percutaneous bypass (PBY) procedure has been utilized in clinical studies for treatment of cardiac arrest patients. However, a recent survey of such PBY procedures in 51 cardiac arrest patients demonstrates the criticality of rapid initiation of the PBY procedure. Of the 51 patients surveyed, 19 had flow established within 15 minutes of cardiac arrest, while 32 patients did not have flow established within 15 minutes of cardiac arrest. Of the 19 patients which received PBY within 15 minutes, all survived initially, and 13 of the 19 were discharged from the hospital. Of the 32 patients which did not receive PBY within 15 minutes of cardiac arrest, none survived. Thus, a critical aspect of successful PBY procedure is rapid initiation.
A drawback of known bypass circuits and procedures is the time required for setting up the circuit preparatory to performing the procedure. Specifically, any support apparatus first must be located, sterilized, assembled and attached to appropriate sterilized circuit tubing. Then, the entire circuit must be primed with a biocompatible fluid, such as blood or saline, to completely flush out any air pockets in the circuit. If present, such air pockets could result in an air embolism passing through the circuit into the patient, which could cause death or serious injury to the patient.
Preassembled PBY circuits are known. For example, one known system includes a femoral access cannulae kit, a hardware assembly and a preassembled and sterilized circuit of tubes for connecting the femoral cannulae and the various hardware. The hardware generally is assembled on a cart, and includes a blood pump, a membrane oxygenator, a gas supply, and a heat exchanger. However, when this system is set up and primed, fluid is required to flow up and down through various segments of the circuit, which traps air at certain high points in the circuit. Thus, safe assembly of the system circuit includes 74 steps, 30 of which are directed to priming procedures that include manipulating and tapping tubing to eliminate air traps and bubbles. Although a few clinicians have found success with this system by training a highly skilled team for rapid set-up, the large number of steps required for set-up and priming, and the criticality of response time required for successful procedure, have intimidated users and discouraged widespread use of a PBY system and procedure in cardiac arrest patients. Accordingly, a need exists for an improved preassembled bypass circuit having a rapid priming configuration.